I used it the first year out and again last year and will this year. I did not see any problems using it on calves. Matter of fact we had some that went to a different farm that didn't get Long Range. At weaning standing side by side the difference was very noticable. Pasture conditions were similar, genetics, other management, etc. was all similar.
But the final answer was in the fecals. The fecals off the calves that had Long Range, even thought they were dosed at smaller size, were still clean. The calves without it obviously were not clean.